There may be some very slight advantages to feathers, but I think they are outweighed by advantages of vanes:

(1) Durability - a few thorns or twigs poking into your quiver while walking in the woods can do some real damage to feathers - not so much with vanes;

(2) Weatherproof - waterproofing agents for feathers will only work so well, if it rains, eventually you have soggy, ineffective feathers;

(3) NOISE - feathers make much more noise than vanes. If you keep your quiver attached to your bow while hunting, this is a constant issue.

Shoot vanes with a compound, save the feathers for your recurve or long bow.

Helpful Hint: When your vanes or feathers seem a little beat up, try steaming them with a steamer, the steam from an ironor a tea kettle. The vanes will straighten out, and feathers will come back to life almost like magic.